The present invention concerns an apparatus for sealing elevator car doors and, in particular, an acoustical seal for automaticly actuated doors on elevator cars.
The problem of sound damping exists in high speed elevator cars because the travel and air noises produced in the shaft increase proportionately with an increase in the speed of travel. These noises penetrate through every opening into the interior of the car and thus reduce the traveling comfort. Known methods of sound damping, such as utilizing damping material filling in the case of double-walled walls and doors, as well as quietly operating ventilation systems, are capable, together with vibration damping equipment, of achieving an appropriate effect. However, acoustic experiments show that even the smallest openings let a great deal of sound through. In relation to a door, this means that a door gap of, for example, one per cent of the entire door opening cross section lets one third to one half the sound volume produced outside the door through into the interior of the car.
In an automatic car door, there are a number of passages in the shape of small air gaps located between movable and fixed parts. These passages must be present in order to avoid direct frictional contacts. Such air gaps typically are present at the following locations: At the bottom of the door between the door sill and the door leaf lower edges, laterally between the door leaf surface and the entry side posts, between two door leaves in the case of telescopic doors, and at the top of the door between the entry abutment and the door leaf upper edge. A partial solution to this problem is to build the elevator car parts to narrow tolerances and use very accurate production and assembly operations in order to reduce these air gaps to a minimum amount. This is an expensive production method which does not entirely solve the problem.
It is disclosed in the U.S. Pat. No. 3,425,162 that this problem is usually ignored and that these air gaps are consequently not sealed off at all. The large passages which transmit sound, as mentioned above, are easily recognizable in the FIGS. 1 to 5 of this patent specification.